N. G. Chuprina

Information media based on electron donor oligomers with different structures

Information properties of recording media for photothermoplastic techniques were investigated. The films consisted of oligomer composites based on carbazole containing co-oligomers of linear and radial structures with branching centers on silicon and germanium atoms. It was ascertained that the media based on the radial oligomers possessed high holographic sensitivity because of the high plasticity and its ability to accumulate volume electric charge during the exposure. Examples of practical applications of the investigated recording media are presented.

Croconium dye as a sensitizer of photothermoplastic holographic media for the near-IR region

This paper discusses the spectral and photoconductive properties of films based on a co-oligomer of glycidylcarbazole with additives of croconium dye in comparison with similar films with squarylium, merocyanine, and cationic polymethine dyes. It is concluded that croconium dye, like merocyanine dye, belongs to the electron-nonsymmetric organic dyes. The possibility of using croconines as sensitizers of photothermoplastic holographic recording media for the near-IR region is demonstrated for the first time. The lower holographic sensitivity of recording media with croconium dye by comparison with squarylium and merocyanine dyes is associated with the presence of deep traps for charge carriers, which are formed by the molecules of an intraionic dye and are liberated when heated in the process of development of the holograms.

Sensitization of Photosemiconducting Properties of Holographic Recording Media Based on Glycidylcarbazole Cooligomers by Organic Dyes

Photophysical and information properties of the holographic recording media (HRM) based on films of ferrocenyl-containing siloxane oligomer, glycidylcarbazole-butylglycidylic ether cooligomer, ferrocenemethylated oligoglycidylcarbazole, and cooligomer of o-carboxybenzoilferrocene glycidylic ether doped with squarilic dye and(or) with merocyanine dye based on ferrocene and tetranitrofluorene are investigated. It is found that the holographic sensitivity is absent for the media based on ferrocenyl-containing siloxane oligomer, and that the holographic sensitivity is present for the films based on glycidylcarbazole. It has been found that the holographic sensitivity and the photoconductivity of the media based on glycidylcarbazole cooligomers increases with the ferrocene content. This effect has been explained by the influence of iron ions on the rate of singlet–triplet conversion in photogenerated pairs of charges.

EFFECT OF THE STRUCTURE AND CONTENT OF CARBAZOLYL-CONTAINING CO-OLIGOMERS ON THE DIFFRACTION EFFICIENCY OF HOLOGRAPHIC RECORDING MEDIA

We have established that as the content of glycidyl carbazolyl fragments increases in their copolymers with α-naphthyl glycidyl ether, the photoconductivity of the films increases but the diffraction efficiency of the holograms decreases. Media based on bromine-containing co-oligomers are more holographically sensitive due to the high surface discharge rate for the films during exposure and formation of a latent electrostatic image.

Donor Oligomer Based Film Heterostructures Doped with Squarilium Organic Dye and their Photoelectric Properties

The new heterostructures comprising a squarylium dye (SQ) film deposited onto a oligo-N-epoxypropylcarbazole (OGC) film have been created, and their photoconducting, photodielectric, and photovoltaic properties have been studied. The OGC/SQ heterostructures exhibit the photodiode properties. It is concluded that the p–n junction in these heterostructures is ensured by the hole character of conductivity in the oligomer and the bipolar conductivity of the deposited dye film.

PHOTOVOLTAIC CHARACTERISTICS OF FILM COMPOSITES BASED ON GLYCIDYLCARBAZOLE COOLIGOMER WITH SYMMETRICAL CATIONIC POLYMETHINE DYES

It was found that film composites based on carbazolyl-containing cooligomer with additions of cationic polymethine dyes exhibit photovoltaic characteristics in the absorption region of the dyes. If the length of the polymethine chain is reduced the value of the photovoltaic response is increased as a result of decrease in the energy of the highest occupied orbital of the dye molecule. In samples of the composite films with free surface area the photovoltaic effect is determined by diffusion of the more mobile positive carriers (the Dember effect) and by their recombination time.

Effect of External Electric Field on Diffraction Efficiency of Polarized Holograms in Films of 4-[(2-Nitrophenyl)Diazenyl]Phenyl Methacrylate Copolymer With Octyl Methacrylate

Holograms with a plane wavefront for parallel and orthogonal orientation of polarization of the light beams were obtained in films of the 4-[(2-nitrophenyl)diazenyl]phenyl methacrylate copolymer with octyl methacrylate, and the effect of an external electric field on their diffraction efficiency was investigated. Two effects from the electric field on the diffraction efficiency of the reconstructed holograms were observed: a fast effect leading to decrease of the diffraction efficiency and a slow effect leading to increase of the diffraction efficiency in the reconstructed holograms. The mechanism of formation of the latent holographic image and the effect of the external electric field on it are due not to the photosemiconducting properties of the films but to optical anisotropy in the isomers of the azobenzene groups and the formation of regular surface relief in the films.

Effect of Oligomer Structure on the Diffraction Efficiency of Holographic Recording Media

A study was carried out on the photophysical properties of photothermoplastic holographic recording media based on film composites derived from linear and branched cooligomers. The diffraction efficiency of the recorded holograms was enhanced by using branched oligomers in the holographic recording media.

Peculiarities of holographic media based on electron donor oligomers of linear and radial structures

The information properties of holographic recording media for photothermoplastic recording with films of oligomer composites based on carbazolyl-containing linear and star co-oligomers with branching centers on silicon and germanium atoms have been studied. The media based on the star oligomers possess higher holographic sensitivity due to greater plasticity and ability to accumulate space electrical charge during exposure. The buildup of space electrical charge results from the capture of photogenerated holes by energy traps created by dimers formed from terminal carbazolyl groups, whose amount is larger in macromolecules of radial oligomers than in linear oligomers.

Holographic Recording Media Based on Poly‐N‐Epoxypropylcarbazole Films Doped with Organic Dyes

A comparative analysis of the recording media based on poly‐N‐epoxypropylcarbazole films doped with cationic, anionic, and intraionic organic dyes has been carried out for the purposes of holographic interferometry. It is shown that in the case of application of intraionic dyes recording media have satisfactory information characteristics. The use of anionic and cationic dyes does not give a positive result because of the absence of the photoconductivity effect in the anionic dyes and of the high electrical conductivity of the films on increase of the temperature of the cationic dyes. The effect of long‐term storage of a latent image in the films with intraionic dyes makes it possible to use them for recording holograms with several exposures.